This application relates to a scroll compressor wherein a clutch prevents rotation of a powered shaft in a reverse direction.
Scroll compressors are becoming widely utilized in refrigerant compression applications. In a scroll compressor, a pair of scroll members each include a base and generally spiral wrap extending from the base. The wraps interfit to define compression chambers. A shaft drives one of the two scroll members to orbit relative to the other. As the one orbits, the size of the compression chambers is decreased. A refrigerant entrapped in the compression chambers is compressed.
Scroll compressors raise many design challenges. One design challenge occurs at shutdown. When a scroll compressor is stopped, refrigerant which may be trapped at centrally located compression chambers may expand. This can cause the orbiting scroll member to be driven in an opposed direction to that in which it is typically driven. This is an occurrence known as reverse rotation, and is somewhat undesirable. Reverse rotation can result in undesirable noise, etc.
One means of preventing such reverse rotation is the use of a one-way clutch, which typically is placed around an upper portion of the shaft, and prevents the orbiting scroll from being driven in the reverse direction. However, one other type of reverse rotation occurs if the motor for the scroll compressor is miswired. If this occurs, then it is possible the scroll compressor will be driven at high speeds in the reverse direction.
With the prior art clutch, when the scroll compressor is driven at a high torque and speed in the reverse direction, the clutch can sometimes fail.
It is thus the goal of this invention to develop a scroll compressor wherein there is a safety to protect the clutch in the event of powered reverse rotation.
In the disclosed embodiment of this invention, a clutch is positioned at a location such that it acts to prevent reverse rotation of the shaft of the scroll compressor. When the compressor is rotated in a forward direction the device is moved to a normal position at which it does not interfere with the rotation of the shaft. However, if the shaft should be driven in the reverse direction it then prevents further rotation of the shaft.
In one embodiment, the clutch is provided by a washer positioned at an end of the shaft remote from the compressor pump unit. The washer preferably provides a thrust force along the length of the shaft. The washer has a tab which is brought into contact with a stop on a housing when driven in a forward position. The tab is driven into a notch in the shaft to prevent reverse rotation of the shaft when driven reverse rotating occurs. Friction between the shaft and the washer causes the washer to move between the two positions.
The washer is preferably mounted within a housing bore in a housing member, which may also be a lower bearing mount. The washer has a smaller size than the housing bore, such that the washer can move between these two positions.
These and other features of this invention will be best understood from the following specification and drawings, the following of which is a brief description.